>-----Original Message----- >From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] >Sent: 05 July 2006 14:06 >To: Microcontroller discussion list - Public. >Subject: Re: [EE] Analog Level shifters > > >On Wednesday 05 July 2006 17:20, Vasile Surducan wrote: >> On 7/5/06, Wouter van Ooijen wrote: >> > > The input signal is 20v peak-to-peak (-10v to +10v) ac 14Mhz rf >> > > signal. and i want to shift it to ( -15v to +5v ). I >looking for >> > > a way to do it >> > > without using additional power supply. >> > >> > a suitable transformer, with the 0 of the secondaryt at -5V? >> +10v - (-10V) = 20V swing >> +5V - (-15V) = 20V swing too >> Pass the signal via a capacitor and fixe the DC level at the right >> value(ie -5V). The question is how you've get 20Vpp/14Mhz RF signal >> (meaning sinusoidal) and what you're doing with it. >> Vasile > >Thanks for your replies, >The actual problem is , i am modifying a rf transceiver board >(rf id) , for >more power. There is low power transceiver ic (TI S67 00) on >the board, which >do all the modulation and demodulation (only for low power >output). I need to modify it to get more power output and more >range for rf id tag. I added a power amplifier on transmitter path. > >For the receiver path, the rx pin of IC is limited to 5V, so i need to >attenuate the rx signal, without losing the data on its >envelope. direct >resistance attenuation will affect the signal strength >(envelope). so i >thought of shifting down the signal and feeding it to the IC. Do the receiver specs really allow negative voltages which far exceed it's maximum allowable positive input voltage? Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist